Stereo slide viewer and stereo slide mount

ABSTRACT

A stereo slide viewer can appreciate a stereo image without cutting a roll film photographed by a stereo camera. A film feeder 3 for feeding a roll film F is mounted at the rear of a table 2 of the stereo side viewer 1, and a pair of right and left projection lenses 5R and 5L are provided at the intermediate of the table 2. A pair of right and left focal plates 9R and 9L are mounted at the front of the table 2, and eyepieces 11R and 11L are installed oppositely at the focal plates 9R and 9L. The back surface of the film feeder 3 is illuminated by an illuminator, and one set of images are focused on the right and left focal plates 9R and 9L through the windows of the film feeder 3.

This application is a continuation of application Ser. No. 08/730,823,filed Oct. 17, 1996, now U.S. Pat. No. 5,720,538.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stereo slide viewer and a stereoslide mount and, particularly, to a stereo slide viewer which can use aroll film and a stereo slide mount having film positioning means.

2. Description of the Prior Art

A conventional stereo slide viewer has a structure that one stereo slidemount is inserted so that an image can be seen by two eyes. A developedroll film is cut at each frame, mounted in the stereo slide mount andthen appreciated. In this case, it is convenient if there is a stereoslide viewer that can appreciate the roll film of long winding withoutcutting.

Even if the roll film is finally cut at each frame and mounted in thestereo slide mount, it is considered that the stereo slide mount isadvantageous in the improvement of the efficiency of the mounting workif the roll film can be detected at the suitable picture mask amount inthe roll state. This is because it is necessary to mask thenon-duplicated parts occurring at the left edge of the left picture andthe right edge of the right picture due to the difference of the visualfields of right and left photographing lenses when the slide taken by ageneral-purpose stereo camera having no lens shifting mechanism ismounted in the stereo slide mount. Since the width to be maskedincreases or decreases according to the distance of an object, it isnecessary to select the stereo slide mount having a suitable windowwidth from a plurality of types of stereo slide mounts having differentwindow widths or to adjust the distance between the right and leftfilms. Heretofore, this mounting work is manually conducted. The ratioof the degree of the work depending upon intuition and experience islarge, and an error of selecting the mount or mounting position of thefilm feasibly occurs.

It therefore becomes necessary to solve the above-mentioned technicalsubject to provide a stereo slide viewer which can observe a stereoimage in the state of a roll film, a stereo slide viewer which candetect a picture mask amount at the time of mounting in the state of aroll film, and a stereo slide mount in which positioning at the time ofmounting is facilitated. The object of the present invention thereforeis to solve the above-mentioned technical subject.

SUMMARY OF THE INVENTION

In order to accomplish the above-mentioned object, the present inventionprovides a stereo slide viewer comprising two right and left opticalsystems each including a projection lens, a focal plate and an eyepiece,and a film feeder having a pair of front and rear windows along afeeding direction of a film, wherein pictures in said pair of windows ofa roll film loaded in the film feeder are individually projected to theright and left focal plates so that stereo images can be appreciated bytwo eyes.

The present invention further provides a stereo slide viewer furthercomprising an image projection magnification adjusting mechanism, adistance adjusting mechanism of the focal plates, and an interlockingmechanism of the projection magnification adjusting mechanism and thefocal plate distance adjusting mechanism, wherein the inside edges ofthe right and left focal plates are brought into coincidence with theinside edges of the projection pictures on the focal plates by theinterlocking mechanism irrespective of the projection enlarging ratio.

The present invention furthermore provides a stereo slide viewer furthercomprising punching units mounted above or below a pair of windows ofthe film feeder, wherein a notch can be formed at a predeterminedposition of an upper or lower edge of the film loaded in the film feederand a stereo slide mount comprising a base frame and a cover framealigned with two rectangular windows, wherein a positioning unit forbringing the pictures of two films into coincidence with the windows byengaging with the notches of the film formed by the punching units isformed on the film placing surface of the base frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a stereo slide viewer of claim 1;

FIG. 2 is a perspective view of a manual film feeder;

FIGS. 3(a) and 3(b) are explanatory views showing the state of adjustinga distance between the optical axes of projection lenses;

FIG. 4 is a front view of a photographed 135 roll film, illustrating anexample of a picture array of a stereo camera;

FIG. 5 is a front view of a cutting mark projected portion of a focalplate;

FIG. 6 is a perspective view of a motor-driven film feeder;

FIG. 7 is a plan view of a stereo slide viewer of claim 2;

FIG. 8 is a front view of a focal plate for detecting a mask amount;

FIG. 9 is an exploded perspective view of a punching unit;

FIGS. 10(a) and 10(b) are front views of a film in which notches areformed by the punching unit;

FIG. 11 illustrates a stereo slide viewer of claim 14, wherein FIG.11(a) is an upside down inverted back view of a cover frame, FIG. 11(b)is a front view of a base frame, FIG. 11(c) is a sectional view of FIG.11(a), and FIG. 11(d) is a sectional view of FIG. 11(b);

FIGS. 12(a), 12(b), 12(c) and 12(d) are upside down inverted back viewsof a cover frame of a stereo slide mount of claim 15;

FIG. 13 is a plan view of a stereo slide viewer of claim 12; and

FIG. 14 is an explanatory view of an interlocking mechanism of apunching unit of a stereo slide viewer of claim 12 to a focal plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described in detail.FIG. 1 illustrates a stereo slide viewer 1, wherein a film feeder 3 forfeeding a roll film F of a long winding is mounted at the rear of atable 2, a pair of right and left projection lens holders 4R and 4L areprovided at the back and forth intermediate portions of the table 2, andprojection lenses 5R and 5L are mounted at the projection lens holders4R and 4L. Nuts are formed at the projection lens holders 4R and 4L.Feed screws 6 installed at the table 2 is coupled to the nuts of theprojection lens holders 4R and 4L by ball screw mechanisms. Left-handthreads and right-hand threads are cut symmetrically from theintermediate portion to the left and the right. A lens distanceadjusting knob 7 mounted at the end of the feed screw 6 is rotated toseparate or approach the right and left projection lens holders 4R and4L in a direction perpendicular to the optical axis, thereby adjustingthe distance between the optical axes of the projection lenses 5R and5L.

A pair of right and left focal plates 8R and 8L are mounted at the frontof the table 2, and focal plates 9R and 9L of the entire mat surface aremounted at the focal plate holders 8R and 8L. Eyepiece holders 10R and10L opposed to the focal plates 9R and 9L are fixed to the front end ofthe table 2, and eyepieces 11R and 11R are mounted at the eyepieceholders 10R and 10L. The eyepiece lense 11R and 11R are moved back andforth by rotating a lens barrel to thereby adjust the dioptric power tomeet the user's eyes. It is desired to set the pitch between the centersof the focal plates 9R and 9L and the eyepieces 11R and 11L to about63.5 mm of human standard pitch between two eyes.

A semicircular reflecting plate 12 is fixed to the rear end of the table2, an illumination bulb 12 is mounted in an inner space formed by thereflecting plate 12 and the film feeder 3 to constitute a diffusinglight source, thereby uniformly illuminating the back surface of thefilm feeder 3.

FIG. 2 illustrates the film feeder 3, wherein an openable retainingcover 15 is pivotally secured to a film guide table 14 having guideslots of the width equal to that of the film. Windows 16R and 16L of thesize and the pitch corresponding to those of a picture array format ofthe stereo camera are provided at the right and left of the film guidetable 14 and the retaining cover 15.

The film feeder 3 of FIG. 2 corresponds to that of the stereo camera ofthe picture array format in which one picture of other set is insertedbetween a pair of right and left pictures. In addition, there are stereocameras of various picture pitches in which a pair of right and leftpictures are disposed adjacently, or other two sets of pictures aredisposed in two frames between a pair of right and left pictures, andthe film feeder can be replaced with the film feeder of the window pitchfor each of the stereo cameras.

When the film feeder 3 is replaced, the lens distance adjusting knob 7is operated to adjust the distance between the projection lenses 5R and5L so that the centers of the projection lenses 5R and 5L are disposedon a straight line for connecting the centers of the right and leftfocal plates 9R and 9L to the centers of the windows 16R and 16L of thefilm feeder 3 as shown in FIGS. 3(a) and 3(b), thereby focusing a set ofimages on the right and left focal plates 9R and 9L.

Identifying means such as an electric contact or a type identifying holeis provided at the film feeder and an electric, magnetic or opticalsensor is provided in a stereo slide viewer body to constitute a filmfeeder identifying mechanism, and a motor is disposed in a distanceadjusting mechanism of the projection lenses 5R and 5L, and the distancebetween the projection lenses 5R and 5L may be automatically adjusted inresponse to the type of the film feeder by a controller.

The film feeder 3 illustrated in FIG. 2 is used for a 135 film. Asprocket wheel 17 to be engaged with the perforations of the 135 film ismounted at the film guide table 14, and a roll film F can be fed byrotating a feed knob 18 fixed to the end of the shaft of the sprocketwheel 17.

Though omitted in drawings, a film supply spool and a film take-up spoolare mounted at both ends of the film guide table 14 to provide a windingand rewinding mechanism similar to the general-purpose camera, a rollfilm is taken up on the film take-up spool from the film supply spool,and may be rewound on the film supply spool after the appreciation. Afeeding mechanism or a take-up spool driving mechanism by a pinch rolleris used instead of the feeding mechanism by the sprocket wheel 17 tothereby feed the film having no perforation such as a 120 roll film.

FIG. 4 illustrates an example of a picture array format of a stereocamera. Pictures are disposed from the head of a 135 roll film in theorder of 1R, 2R, 1L 2L, 3R, 4R, 3L, 4L, . . . , and upside down and leftside right inverted images are exposed at the pictures. The upside downand left side right inverted images on the roll film F are inverted bythe projection lenses 5R and 5L of the stereo slide viewer 1, focused aserect images on the focal plates 9R and 9L, and the erect stereo imagecan be appreciated through right and left eyepieces 11R and 11L.

The applicant of the present invention has proposed a stereo camera inwhich cutting marks CM and frame numbers nR and nL to be an index ofcutting between the pictures of a film F are exposed at the time oftaking a picture, by referring to FIG. 4. By referring back to FIG. 2,cutting mark projection window 19 and a frame number projection window20 are provided at the film guide table 14 and the retaining cover 15,and a cutting mark projected portion 21 and a frame number projectedportion 22 are provided on the focal plate 9R, thereby accuratelyaligning the pictures of the film F with the windows 16R and 16L andvisually recognizing the frame number.

Referring to FIG. 5, an index line L_(REF) similar to the cutting markCM is printed on the cutting mark of projected portion 21 of the focalplate 9R, and the relative positional relationship between the indexline L_(REF) and the picture area of the focal plate 9R is equal to thepositional relationship between the photographed picture on the rollfilm F and the cutting mark CM. Therefore, if the cutting mark CMprojected to the cutting mark projected portion 21 is brought intocoincidence with the index line L_(REF), the position of the windows 16Rand 16L coincide with the pictures of the film F.

Furthermore, the film feeding can be automated by utilizing the cuttingmark CM. Referring to FIG. 6, an optical sensor 34 is provided in thecutting mark projection window 33 of the retaining cover 32 of amotor-driven film feeder 31, and a feed controller (not shown) forcontrolling a winding motor 35 according to the cutting mark detectionsignal of the optical sensor 34 is provided.

The head of the roll film F is locked to a take-up spool 36, and theretaining cover 32 is superposed on a film guide table 37. When a feedexecution signal is input to the feed controller by operating means suchas a feed button, the winding motor 35 is rotatably driven to wind theroll film F. When the cutting mark CM on the first picture is detectedby the optical sensor 34, the winding is stopped, and the pictures ofthe first set are disposed at windows 38R and 38L.

Frame feeding or one frame rewinding is executed by the feed controllerin response to the operation of the button, stopped at the positionwhere the corresponding cutting mark is detected by the optical sensor34, and the stereo pictures can be continuously appreciated only by theoperation of the button.

In the roll film photographed by the stereo camera of the picture arrayformat illustrated in FIG. 4, after the set of the 1R and 1L areappreciated, when the film is fed by one frame, the 2R and 2L arerepresented in the windows, and it is then necessary to feed threeframes to observe the 3R and 3L. In this manner, a labor hour ofalternately feeding the one frame and the three frames must be required.In order to eliminate the labor hour, the means for automaticallycontrolling the winding mechanism by the motor based on the picturearray format of the stereo camera is effective.

Though omitted in the drawings, as the automatic control means forwinding, there is means for reading data by coating the edge of the rollfilm with a magnetic recording material to record position informationand frame number information and providing a magnetic head at a filmguide table. In this case, the magnetic head is provided at the filmguide table, the position information and the frame number informationare recorded by data recorder/reproducer, or the magnetic head and thedata recorder are provided in the stereo camera to record theinformation on the film at the time of taking a picture.

If information is recorded by the film feeder, a roll film is firstmounted at the film feeder, the film is fed manually or by a motor toalign the pictures with the windows, and the data recorder/reproducer isoperated at the position to record the information on the respectivepictures.

If magnetic recording information is used, various information can berecorded in addition to the position information and the frame numberinformation. For example, jump information is recorded on the picturefailed to take a picture in the one roll film to automatically skip theunnecessary picture at the time of feeding to next picture.

The above-mentioned stereo slide viewer 1 has fixed ratios of visualfields on right and left pictures. In a stereo camera having a mechanismfor adjusting a distance between the optical axes of photographinglenses as proposed by the applicant of the present invention, optimumstereo effect is obtained in all pictures of the film in which aparallax is corrected in response to the photographing distance.However, as described above, in the film which is taken by a stereocamera having no mechanism for adjusting the distance between theoptical axes, there might be unnatural in the stereo effect according tothe photographing distance of an object. In order to eliminate thisproblem, referring to FIG. 1, picture mask shutters 39R and 39L forshielding the outsides of the right and left focal plates 9R and 9L areprovided or shutters for shielding the insides of the right and leftwindows of the film feeder 3 are provided, and the outer areas of theerected pictures are suitably masked in response to the photographingstate to appreciate by the optimum stereo effect. The picture maskshutters 39R and 39L may be adjusted manually or a motor by providing anadjusting mechanism for interlocking them symmetrically by feed screws.The mask amounts of the respective pictures are determined by testappreciation, the mask amounts are recorded on the film F as themagnetic recording information as described above, and the shutterdriving motor is automatically controlled by the controller, and hencethe manual operation can be eliminated.

A stereo slide viewer 41 shown in FIG. 7 has a manual or motor-drivenfilm feeder 31 described above mounted at the rear of a slide guidetable 42, and a projection lens base 43 mounted at the front of the filmfeeder 31 so that the film feeder 31 and the projection lens base 43 areslidable in a direction of an optical axis. A pair of projection lensholders 44R and 44L are mounted at the projection lens base 43. Lensdistance adjusting mechanisms by ball screws as described above areprovided at the projection lens holders 44R and 44L to adjust thedistance between the optical axes of the projection lenses 45R and 45L.

A pair of right and left focal plate holders 46R and 46L are mounted atthe front of the slide guide table 42, and the focal plates 47R and 47Rof the focal plate holders 46R and 46L can be replaced. Similar to thestereo slide viewer 1 of FIG. 1, eyepiece holders 10R and 10R opposed tothe focal plates 47R and 47L are fixed to the front end of the slideguide table 42, and a dioptric power can be adjusted by rotating thelens barrel of the eyepieces R and L of the eyepiece holders 10R and10L. A diffusing light source of a semicircular reflecting plate 12 andan illuminating bulb 13 is provided at the rear end of the slide guidetable 42.

The focal plate holders 46R and 46L are mounted, similar to theprojection lens holders 44R and 44L, at a ball screw mechanism. Feedscrews 48 of the ball screw mechanism are right-hand threads at theright side and left-hand threads at the left side. The right and leftfocal plate holders 46R and 46L are separated or approached in adirection perpendicular to the optical axis by rotating the focal platedistance adjusting knob 49 mounted at the end of the feed screw 48, andthe distance can be adjusted in a predetermined range in the directionapproaching to each other from the reference pitch at the pitch of thefocal plates 47R and 47L.

Two cam plates 50 and 51 for individually moving the film feeder 31 andthe projection lens base 43 are mounted at the intermediate position ofthe feed screw 48. Tappet rods 52 and 53 are interposed between the filmfeeder 31 and the cam plate 50 and between the projection lens base 43ad the cam plate 51, and the film feeder 31 and the projection lens base43 are brought into pressure contact with the cam plates 50 and 51 viathe tappet rods 52 and 53 by being energized by tensile coils 54 and 55.Therefore, the film feeder 31 and the projection lens base 43 areinterlocked to the rotations of the cam plates 50 and 51 by rotating thefocal plate distance adjusting knob 49, and moved back and forth in arange between the foremost position of 1:1 of an image magnification andthe rear enlarged projection position. The two cam plates 50 and 51 areso formed that the projected images on the focal plates 47R and 47Lbecome the moving ratio of always maintaining a focused state within themoving range of the film feeder 31 and the projection lens base 43,thereby enlarging the projected picture at an arbitrary magnification.

When the film feeder 31 and the projection lens base 43 are moved in adirection of enlarging the projected picture, the focal plate holders46R and 46L are interlocked to approach to each other at the distance,and erected images on the right and left focal plates 47R and 47L aremasked at the outsides by the picture frames of the focal plates 47R and47L.

At this time, if it is assumed that the real picture widths of thestereo slides and the picture widths of the focal plates 47R and 47L are30 mm, the projection picture width when the pictures of the slides are,for example, enlarged and projected becomes 30×30/29=31.034 (mm), andthe difference of the projection picture width from the 30 mm of thepicture widths of the focal plates 47R and 47L is 31.034-30=1.034 (mm).That is, if the focal plates 47R and 47L are disposed at the initialpositions shown in FIG. 7, the enlarged projection picture exceeds1.034/2=0.517 (mm) to the right and left outsides of the focal plates47R and 47L.

The pitch of the feed screw 48 is the pitch of shifting of the right andleft focal plate holders 46R and 46L of 0.517 mm to the inside in thecase of, for example, of the projection enlarging ratio of 30/29. Theinside edges of the picture areas of the focal plates 47R and 47Lcoincide with the inside edge of the slide projection pictureirrespective of the projection enlarging ratio, the outside area of theprojection picture exceeds the outside of the focal plates to be masked,and the mask area is continuously varied in response to the projectionenlarging ratio. Thus, when the roll film photographed by the stereocamera having no mechanism for adjusting the distance between theoptical axes is appreciated, the projection enlarging ratio is adjustedin response to the photographing state, and the outside area of thepicture is suitably masked to be appreciated with the optimum stereoeffect.

The stereo slide viewer 41 can be used as a mask amount guiding unitwhen the film is mounted in a stereo slide mount by replacing the focalplates 47R and 47L of the entire matted surface with a mask amountdetecting focal plate 56 having a collimation pattern CP having verticallines as main bodies as shown in FIG. 8.

When used as a mask amount guiding unit, a stereo image is observedwhile rotating a focal plate distance adjusting knob 49, the mask amountwhen the front and rear positions of a subject in a close-range view aresubstantially equal to the collimation pattern CP of the right and leftmask amount detecting focal plates 56R and 56L or in the state observedin the depth of the collimation pattern CP becomes a suitable maskamount, and accurate stereo images can be reproduced by mounting thefilm in the stereo slide mount having the window width meeting theconditions.

As shown in FIG. 7, the same number as a mount number is displayed atthe rotary position of the stereo slide mount or a framing mask (aplurality of types of stereo slide mount or a framing mask having a filmpositioning pin and different window widths) proposed by the applicantof the present invention corresponding to the picture shielding ratio ona dial 57 of the focal plate distance adjusting knob 49. Therefore, ifthe number of the dial 57 is observed when the subject in a close-rangeview is disposed at the front or rear position substantially equal tothe collimation pattern CP of the mask amount detecting focal plates 56Rand 56L or becomes the state observed in the depth of the collimationpattern CP, the suitable number of the stereo slide mount or the framingmask can be recognized, and the mount can be easily and accuratelyconducted.

The mounting work of the film having no perforation such as a 120 filmcan be facilitated similarly to the 135 film by providing punching units61R and 61L in the film feeder 31 as shown in FIG. 7.

Referring to FIG. 9, a die 62 of the punching unit 61 is coupled to thefilm guide table 37 of a film feeder 31, and a punch holder 63 and afilm retaining arm 64 are vertically rotatably secured to the die 62.Compression coiled springs 65 and 66 are mounted at the die 62 and thefilm retaining arm 64 as well as the film retaining arm 64 and the punchholder 63, and the punch holder 63 and the film retaining arm 64 arefloated from the die 62. A cam 67 is disposed above the punch holder 63,and the punch holder 63 and the film retaining arm 64 are moved down byrotating an operating lever 68 fixed to a cam shaft.

When the cam 67 pushes the upper surface of the punch holder 63, thepunch holder 63 and the film retaining arm 64 are integrally moved down,the film is sandwiched between the film retaining arm 64 and the die 62to be fixed. Then, when the operating lever 68 is further rotated, thepunch holder 63 compresses the compression coiled spring 66 to move itdown, the punch 69 mounted at the end of the punch holder 63 is engagedwith the die 62 to punch the edge of the film F, thereby forming anotch.

When the stereo slide is cut at each one frame, it is not easy toidentify a left side film from a right side film. However, the punchesof the right and left punching units 61R and 61L and the shapes of thedies are differentiated, and the shapes of the notches NR and NL of theright side film FR and the left side film FL are differentiated as shownin FIG. 10, and hence the right side film FR can be identified from theleft side film RL.

FIG. 11 illustrates a stereo slide mount for a 120 film having a coverframe 71 in FIG. 11(a) and a base frame 72 in FIG. 11(b). Projections74R and 74L of the shapes engaged with the notches of the film areprovided at the upper edge of a recess film placing portion 73 formed atthe base frame 72, and the projections 74R and 74L are disposed on thecenterlines of the right and left windows. A film retaining portion 75of the protruding surface engaged with the film placing portion 73 ofthe base frame 72 is formed at the cover frame 71 engaged with the baseframe 72, and the film retaining portion 75 has a symmetrical shapeincluding recesses 76R and 76L corresponding to the protrusions 74R and74L of the base frame 72.

The stereo slide mount is desired to set, similar to the stereo slidemount or the framing mask proposed by the applicant of the presentinvention as described above, the pitch P₁ of the right and left windows77R and 77L of the base frame 72 to about 63.5 mm similar to the pitchof human two eyes. The aspect ratio of the windows 77R and 77L is thesame as or slightly larger than the picture size of the slide film F, sothat the entire picture of the film F can be seen. When one set of slidefilms F cut at each one frame are placed on the film placing portion 73and the notches NR and NL are engaged with the protrusions 74R and 74L,the centers of the windows 77R and 77L coincide with the centers of thepictures of the slide film F.

Referring to FIG. 12, the cover films 71 engaged with the base frames 72of a plurality of types in which the distance of the right and leftwindows 78R and 78L and the widths of the windows are equal to thedistance C₁ of the windows and the width W₀ of the window of the baseframe 72 are equal (#0) to the distances C₁ of the windows is equal andthe widths W of the windows are gradually stepwisely decreased (#1, #1,#3, . . .) are prepared.

When the cover frame 71 of the number obtained by the mask amountdetecting work using the stereo slide viewer 41 is joined to the baseframe 72, the stereo slide of the suitable picture mask amount can beformed in response to the photographing state.

A stereo slide viewer 81 shown in FIG. 13 has no mechanism for adjustinga projection magnification, and has a distance adjusting mechanism ofprojection lenses 45R and 45L and a distance adjusting mechanism offocal plates 47R and 47L equal to those of the stereo slide viewer 41 ofFIG. 7 to be placed. Punching units 61R and 61L are mounted movablyalong the film guide table 37 of a film feeder 31.

Levers 82R and 82L are secured horizontally rotatably to right and leftprojection lens holders 44R and 44L, and the rotating fulcra of thelevers 82R and 82L are disposed at positions equal to the opticalcenters of the projection lenses 45R and 45L. As shown in FIG. 14, oneends of the levers 82R and 82L are engaged with focal plate holders 46Rand 46L, and the other ends are engaged with the punching units 61R and62L. When the focal plate distance adjusting knob 49 is rotated to movethe focal plate holders 46R and 46L in an approaching direction, theinterval of the punching units 61R and 61L symmetrically increases, andthe positions of the notches NR and NL formed at the film F are offsetfrom the centers of the upside down and left side right inverted pictureto the outside, i.e., to the inside of an erected picture. Therefore,when the film formed with the notches in this manner is cut at eachframe and mounted in the stereo slide mount, the near the distance ofthe subject of the film is, the greater the pitch of the pictures isincreased, the outside area of the erected picture is masked by thestereo slide mount, the parallax of the subject in a close-range view iscorrected, and the stereo slide of suitable picture mask amount can beformed in response to the photographing state.

If the notches NR and NL are formed at the film F by the stereo slideviewer 81, since the pitch of the pictures of the film is increasedlarger than the pitch of the pictures of the stereo slide mount to befrequently mounted, there arises the necessity of forming slightlynarrower in the window width of the stereo slide mount so that theperipheral edge of the picture inside the picture is not exposed withinthe window of the mount. However, it is not necessary to record thenumber of the conforming cover frame 71 by detecting the mask amount andto prepare cover frames 71 of various window widths different from thestereo slide viewer 41 in which the notch positions are fixed, but thefilm can be mounted uniformly in the stereo slide mount having apredetermined window width, and hence the mounting work isadvantageously facilitated.

The stereo slide viewer of the present invention as described above canappreciate the roll film of the long winding as it is. Therefore, thelabor hour of replacing the stereo slide mount one by one is eliminated,and the one film can be continuously appreciated.

Even when the film is mounted in the stereo slide mount, the suitablemask amount can be detected before each one frame is cut, and hence theefficiency of mounting process can be remarkably improved.

When the notch is formed at the film having no perforation such as a 120film by the stereo slide viewer having punching units so that the filmis mounted in the stereo slide mount of the present invention, the filmis accurately positioned to sufficiently perform the visual effect ofthe stereo photograph, and hence the complexity and the inaccuracy ofthe mounting work of the conventional stereo slide are eliminated.

The projection magnification varying mechanism and the focal platedistance adjusting mechanism may be constituted instead of a shownmanual type by driving movable units by a servo motor and mounting anelectric, magnetic or optical positional sensor at the movable units tofeedback control it by a position controller. The constitutions of theunits can be modified in a variety of ways within the technical scope ofthe invention, and it should be noted that the present inventionencompasses such modified embodiments, as a matter of course.

I claim:
 1. A stereo slide viewer used in a stereo slide mounting systemcomprising:a source of illumination; a film feeder placed adjacent saidsource of illumination; a pair of projection lenses; a pair of focusplates, each of said pair of focus plates having a collimation patternthereon; a focus plate feed screw coupled to said pair of focus plates,said focus plate feed screw having right-hand threads and left-handthreads with one of said pair of focus plates coupled to the right-handthreads of said focus plate feed screw and the other one of said pair offocus plates coupled to the left-hand threads of said focus plate feedscrew; a dial coupled to said focus plate feed screw; and a linkagecoupling said film feeder and said pair of projection lenses together,whereby the movement of said film feeder and said pair of projectionlenses is related to the rotation of said focus plate feed screw,whereby an outside area of a picture on said pair of focus plates issuitably masked to be appreciated with an optimum stereo effect and anaccurate stereo image can be reproduced by mounting a film in a stereoslide mount having a predetermined window width indicated by said dial.2. A stereo slide viewer as in claim 1 further comprising:a pair ofeyepieces placed adjacent said pair of focus plates.
 3. A stereo slideviewer as in claim 1 wherein:said linkage comprises a cam and tappetrod.
 4. A stereo slide viewer as in claim 1 further comprising:aplurality of stereo slide mounts, each of said plurality of stereo slidemounts having a different window width, wherein said dial indicateswhich one of said plurality of stereo slide mounts to use for mounting afilm to obtain an optimum stereo effect.
 5. A stereo slide viewer as inclaim 1 further comprising:a projection lens feed screw coupled to saidpair of projection lenses, said projection lens feed screw havingright-hand threads and left-hand threads with one of said pair ofprojection lenses coupled to the right-hand threads of said projectionlens feed screw and the other one of said pair of projection lensescoupled to the left-hand threads of said projection lens feed screw,wherein the distance between said pair of projection lenses may bechanged.